I have surprisingly discovered that 5,9-dimethyldeca-4,9-dien-1-al, the aldehyde of formula ##STR1## possesses odorous features of great utility and consequently can be widely utilized in the art of perfumery. Its olfactive character of flowery type is reminiscent of the scent developed by certain plants of the family of liliaceous, more particularly of lily-of-the-valley. Its odour note is "clean," powerful and devoided of fatty tones. This latter aspect is rather surprising since higher aliphatic aldehydes, viz. those aldehydes which possess in the main chain a number of carbon atoms of the order of 8, or higher than 8, develop various odour notes, eminently of fruity type, accompanied however by fatty and waxy notes, especially when used at high concentrations. This fact raises serious problems for perfumers who, in their compounding activity, must often have recourse to complex mixtures in order to mask the unpleasant fatty characters of the aldehydes utilized.
Deca-2,4-dien-1-al for instance develops at low concentration a sweet smell reminiscent of orange. At higher concentration its odour becomes clearly fatty.
Undec-10-en-1-al develops a waxy, rosy odour which for certain of its characters is reminiscent of the odour possessed by citrus fruits. The same odour is presented by undec-2-en-1-al, as well as by decanal and dec-2-en-1-al.
5,9-Dimethyl-deca-4,8-dien-1-al is described as being a compound possessing a sweet, fatty odour with fruity and smoky characters [see U.S. Pat. No. 3,493,619].
The smell of 2,5,9-trimethyl-deca-4,8-dien-1-al has been described as being of "agreably fresh fruity, slightly fatty" type. Finally, in the above mentioned U.S. Patent, 5,9-dimethyl-dec-4-en-1-al is defined as being a compound possessing an odour of "agreably fatty-herbaceous, slightly fruity" type. Concerning their respective odorous properties, the aldehyde of the invention as compared with 5,9-dimethyl-deca-4,8-dien-1-al is characterized by a less aggressive, more pleasant and slightly green character.
Its odour is reminiscent of the flowers of lily-of-the-valley or that of citronellyloxyacetaldehyde giving rise at the same time to a warmer and lighter effect; in contradistinction 5,9-dimethyl-deca-4,8-dien-1-al is more directly reminiscent of dec-9-en-1-al.